Input: cobalt_btns - assorted fixes

 - fix compile errors (keymap is in bdev, not pdev)
 - cdev is no more (must use dev.parent)
 - update copiright notice

Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>